Fix build against PHP 8.6: php_error_docref1() was removed

PHP 8.6 removed php_error_docref1() (php-src UPGRADING.INTERNALS,
"Removed" section); the docref parameter is no longer supported.

The two call sites passed the SMB URL as that parameter, so route them
through a SMBCLIENT_ERROR_URL() helper that folds the URL into the
message on 8.6+ and keeps php_error_docref1() on older versions.

Not fixed upstream: eduardok/libsmbclient-php master still calls
php_error_docref1() as of 2026-07-30.

--- a/php_smbclient.h
+++ b/php_smbclient.h
@@ -129,6 +129,17 @@
 #define TSRMLS_FETCH()
 #endif
 
+/* php_error_docref1() was removed in PHP 8.6. It printed the URL as the
+ * docref parameter, so fold it into the message to keep reporting which
+ * path failed. */
+#if PHP_VERSION_ID >= 80600
+#define SMBCLIENT_ERROR_URL(url, type, fmt, ...) \
+	php_error_docref(NULL, type, "%s: " fmt, url, __VA_ARGS__)
+#else
+#define SMBCLIENT_ERROR_URL(url, type, fmt, ...) \
+	php_error_docref1(NULL, url, type, fmt, __VA_ARGS__)
+#endif
+
 extern php_stream_wrapper php_stream_smb_wrapper;
 php_smbclient_state * php_smbclient_state_new  (php_stream_context *context, int init TSRMLS_DC);
 void                  php_smbclient_state_free (php_smbclient_state *state TSRMLS_DC);
--- a/smb_streams.c
+++ b/smb_streams.c
@@ -688,12 +688,12 @@
 			break;
 
 		default:
-			php_error_docref1(NULL TSRMLS_CC, url, E_WARNING, "Unknown option %d for stream_metadata", option);
+			SMBCLIENT_ERROR_URL(url, E_WARNING, "Unknown option %d for stream_metadata", option);
 			return 0;
 	}
 	php_smb_pool_drop(state TSRMLS_CC);
 	if (ret == -1) {
-		php_error_docref1(NULL TSRMLS_CC, url, E_WARNING, "Operation failed: %s", strerror(errno));
+		SMBCLIENT_ERROR_URL(url, E_WARNING, "Operation failed: %s", strerror(errno));
 		return 0;
 	}
 	php_clear_stat_cache(0, NULL, 0 TSRMLS_CC);